1. Field of the Invention
The present invention relates to electrical cable terminations, more particularly, to controlled impedance cable terminations which are generally used to transmit high-frequency signals in electronic equipment.
2. Description of the Related Art
The purpose of a cable termination is to provide an interconnect from the cable to the electrical device and to provide a separable electrical interconnection between the cable and its operating environment. The characteristic of separability means that the cables are not interconnected by permanent mechanical means, such as soldering or bonding, but by temporary mechanical means.
Currently cables are terminated using a conventional type connector which is also controlled-impedance, such as an SMA (SubMiniature Version A) connector, or the cables are soldered to a printed circuit board (PCB) which is then separably connected to the working environment. The SMA connectors, while being generally the same impedance environment as the cable, have impedance mismatches which cause high-frequency attenuation at the point of interface between the cable and the connector and the connector and its working environment, such as like a PCB. Additionally, these cable terminations often require through holes in PCB's for mounting and, consequently, it can be difficult to design the best possible controlled impedance environment. These types of cable terminations are generally for a single cable and require a substantial amount of PCB area to terminate, thus decreasing the density capability of connections.
Another form of prior art is a system which uses two independent parts to mate several cables to its electrical environment. This system uses one part that is generally soldered to a printed circuit board and another part that is generally mated to several cables. The two pieces can be plugged together to form the controlled impedance interconnection. These systems are better-controlled impedance environments but are limited in the densities at which the cables can be used. That is, the cables require a minimum space between them to achieve the controlled impedance environment and thus only a small number of cables can be terminated in a given area.
Another form of prior art, disclosed in U.S. Pat. No. 7,544,093, is a system which employs removable cables that are held to the device by means of a spring. The cable has a terminal end which makes the signal conductor protrude from the cable terminal end. The terminal is then pressed to the device by means of a spring and the ground shield of the cable is connected to the device by a conductive rubber ground shield that shorts the terminal ground to the device ground.